Excessive oil consumption - part 2
- Thread starter iluvmacs
- Start date
- :
- Mazda P5
Use seafoam. Works wonders in cleaning but not sure if it'll help with oil consumption, put it in gas oil and some through the brake booster to clean everything out.
I used seafoam and it makes a ton of smoke. No idea if it cleans anything. When I took the intake and head off they were still completely covered in soot. I used a wire brush on a power drill to remove it.
What I noticed when I took everything apart is the cylinders are oval, taper, and are on the large side of the factory spec. What that means is that there is lots of piston/ring blow-by, causing increased crankcase pressure. This blows the oil up through the PCV path into the valve area, where more oil is picked up in the blow by gas, and heads right into the intake. The catch can helps, but the engine could also be sucking in blowby gas and oil on the intake stroke when there's a large vacuum in that cylinder, but high pressure from another cylinder on the power stroke.
I'm ready for my 3rd rebuild but this time I'm going to get the cylinders cut to the smallest size that is a true cylinder (no taper, no oval). I just don't know what size piston to buy.
At this point, the car has no value, so I can do WHATEVER I want to it. I'm thinking about standalone ECU and maybe a turbo (I have a focus ST now and it's cool but i still love NA high revs). 100% custom exhaust, probably a full MSP suspension swap (still have the original suspension from 2003 after northern winter salt and 120k miles.
What I noticed when I took everything apart is the cylinders are oval, taper, and are on the large side of the factory spec. What that means is that there is lots of piston/ring blow-by, causing increased crankcase pressure. This blows the oil up through the PCV path into the valve area, where more oil is picked up in the blow by gas, and heads right into the intake. The catch can helps, but the engine could also be sucking in blowby gas and oil on the intake stroke when there's a large vacuum in that cylinder, but high pressure from another cylinder on the power stroke.
I'm ready for my 3rd rebuild but this time I'm going to get the cylinders cut to the smallest size that is a true cylinder (no taper, no oval). I just don't know what size piston to buy.
At this point, the car has no value, so I can do WHATEVER I want to it. I'm thinking about standalone ECU and maybe a turbo (I have a focus ST now and it's cool but i still love NA high revs). 100% custom exhaust, probably a full MSP suspension swap (still have the original suspension from 2003 after northern winter salt and 120k miles.
The bores will have to be measured after tear down, then the machinist should know what size pistons to order. He'll probably have to have the pistons on hand before doing the machine work too.
I've put almost 40k on my JDM engine. It burns barely anything now, a quart in 2-3000 miles. A 5 quart jug gets me through an oil change, 4 quarts initially and one to top off
Yes I agree. Will get measurements after tear down and then order pistons. Would be nice if 0.050" overbite was all that I need but I'm not optimistic. What happens after 0.100" pistons are too small? New block, sleeves, custom piston and rod matching?
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Probably best off with a reman short block at that point. I'd be surprised if it needs more more than .1mm though, you don't see much bore wear on modern engines.
katapaltes
'03 P5, '17 Miata, stock AF
- :
- Dallas, TX
- :
- 2003 Protege5
Out of the blue, I started burning two quarts between oil changes. A car salesman familiar with Ford Focuses to the same era told me to change the PCV valve. I instead cleaned it with intake manifold cleaner and my oil consumption has dropped quite a bit.
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You can get a new PCV valve for less than $2 US.
You probably spent more on the cleaner.
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